Nakahata N, Hayashi A, Suzuki T
Res Commun Chem Pathol Pharmacol. 1982 Apr;36(1):3-15.
The relaxation induced by isoproterenol, A beta-stimulant, appears more markedly at 25 degrees C (pD2 7.98) than at 37 degree C (pD2 6.88) in rabbit intestine. The isoproterenol-induced relaxation was antagonized by treatment with propranolol but not phentolamine at both 25 degree and 37 degrees C, indicating that the relaxation was mediated via adrenergic beta-receptor. The relaxations induced by papaverine, theophylline and MgCl2 were not influenced by temperature change. Basal tissue cyclic AMP content was higher at 25 degrees C than at 37 degrees C, and isoproterenol increased the tissue cyclic AMP content to a similar extent at 25 degrees C and 37 degrees C in the presence of theophylline. The binding of 3H-dihydroalprenolol (3H-DHA) to beta-receptor did not solve the reason of higher sensitivity to isoproterenol at 25 degrees C than at 27 degrees C. At 37 degrees C isoproterenol was more effective in producing a relaxation in the presence than the absence of ascorbic acid (0.057 mM). It is thought that the temperature dependency of the isoproterenol-induced relaxation may be mainly due to the breakdown of isoproterenol in a high temperature.
在兔肠中，β 激动剂异丙肾上腺素诱导的舒张在25℃（pD2 7.98）时比在37℃（pD2 6.88）时更为明显。在25℃和37℃时，普萘洛尔可拮抗异丙肾上腺素诱导的舒张，而酚妥拉明则不能，这表明该舒张是通过肾上腺素能β受体介导的。罂粟碱、茶碱和MgCl2诱导的舒张不受温度变化的影响。基础组织环磷酸腺苷（cAMP）含量在25℃时高于37℃，并且在茶碱存在的情况下，异丙肾上腺素在25℃和37℃时使组织cAMP含量升高的程度相似。3H - 二氢阿普洛尔（3H - DHA）与β受体的结合并不能解释在25℃时对异丙肾上腺素的敏感性高于37℃的原因。在37℃时，异丙肾上腺素在存在（0.057 mM）抗坏血酸的情况下比不存在时更有效地产生舒张作用。据认为，异丙肾上腺素诱导的舒张的温度依赖性可能主要是由于异丙肾上腺素在高温下的分解。
